Air propeller



Sept. 11, 1923.

C. DORNIER AIR PROPELLER Filed March 31 192i /4 llll'l'lllllll J NVENTO R 1 Patented Sept. 11, 1923.

UNITED STATES, PATENT. OFFICE.

CLAUDIUS noimrnn, or rnmnnrcnsnnrnn, GERMANY, ,assxenon, as means ass1oN- MENTS, TO THE FIRM nonmnn-mn'rannnaornn, GESELLSCHAFT mr snscnzafinx'rna mrune, or rmnnarcnsnnrnn, GERMANY, AND cmtrmusmon NIEB, or rnmnnrcnsnnrnn, 'G-EBMANY.

AIR rnorELLnn.

Application filed Hatch 81, 1921. Serial No. 457,544. v

To all whom it may concern:

Be it known that I, CLAUDIUS DORNI'ER,

a citizen of the German Empire, residing at Friedrichshafen, Germany, have invented 5 certain new and'useful Improvements in Air Propellers, of which the following is a specification.

My invention refers to air propellers, and more particularly to an arrangement thereof which will render it possible to utilize the motor power to its full limits even at greatest height.

As may be known, the motor output is kept constant up to very considerable altitudes by the most diverse means. It is therefore imperative that'the propeller shall transmit this said output entirely to the air without any considerable increase in the number of its rotations.

Up to the present, the rigid wooden propeller was dimensioned for an average height. This, however, only allowed of a rather unsatisfactory utilization of the motor power. Attempts were therefore made to obtain an adaptation to the conditions as they gradually altered by means of adjustable air propellers. The majority of the forms of constructions proposed in connection with adjustable propellers of this kind, however, relates to extremely complicated propellerstructures so that the adaptability required is only obtained by the addition of very considerable drawbacks.

My invention is intended toremedy these defects by providin a system of arrangement for the pro e lers of aircraft which will allow of suc drive for the said air propellers as will fully comply with the actual requirements, and in thecase of which two two-bladed air propellers of either the same or different dimension are so disposed the one to the rear of the other that, according to the prevaily one of said'propellers, or else both, can

, be coupled to the driving shaft.

Thus at low heights one of the propellers only will act as the driving. propeller, while the other will, for, the pn'asent,- run light. Only at a (greater-lieight,' at which the overcompresse motor yields air excess beyond the propeller capacity, the second propeller, which isarranged either directly to the rear an adjustment of theingpower or speed conditions of the motor. on

or in front of the other propeller, is likewise coupled to the driving shaft so that in 65 this mannera founbladed propeller will be produced, which is capable of transmitting the full motor output to the air even at a considerably greater height. In this connection I have found it expedient when interconnecting the second propeller to take 5 due care that the coupling shall be etFected' in such a manner that the wing blades will be displaced at 90 relatively to' each other as required for a four-bladed propeller. In

.this case, the two propellers must be interlocked, say, by means'of a claw coupling or peller, there may be secured a suitable regulation of the capacity, and this, for instance, in such wise that the angle will only gradually be augmented to 90, so that'the maximum capacity will be obtained only by steps.

In conclusion let it be notedthat the coupling may be effected either indirectly or 7 directly automatically in mere dependency upon the speedof t metric air pressure, and this, for'example, in v such a manner that as soon as the speed ex-- ceeds a certain maximum, the auxiliary pro-. peller will be thrown into action.

In the drawings afiixed to this specification and forming part thereof a propeller system embodying my invention is illustrated by way of example.- v 1 Referrin to the drawings there is keyed upon the riving shaft 1 the-hub 2 of the main propeller 3, whereas the hub 5 of the auxiliary propeller 6 is rotatably' mounteg on the slightly reducedend 4"of thesai shaft. The hi1b 2 ofthe main propeller 3 is provided :with; a toothedcouplingflmember 7 which,-whe1itli e driving shaft 1 executes an axial motion, in the direction indicated by the arrow" 8, is adapted to engage suitable notches-9 formed in the hub 5 of the auxiliary propellers. Axial displacement of the shaft 1 can =eifected by aid e-'motor orthe baroof a double armed lever 11 pivoted to the casing at and carrying pins .12 engaging in a circumferential groove 13 of the shaft, the free end of lever 11 being linked to a connecting rod 14 located in bearings 15. A spring'16 serves for holding the lever in normal position. Axial motion of the fixed propeller 3 is prevented by claws 17, 18 fixed to the case and which "overlap the flange of the propeller hub.

The manner of operation of the improved air propeller drive is such that at low height only the air propeller 3 will enter into operation, whereas propeller 6 will run along empty. Only after there has been created an excess of output on the part of the motor owing to a reduction of air resistance the claw coupling 7, 9 will be thrown in, so that now both propellers ,3

and 6 will operate conjointly. '7 With regard to the said claw coupling 7 9, due care is taken that the angle of the propeller blades will invariably amount to 90, so that consequently a four-bladed propeller of the usual type will come to be produced.

I claim:

1. Aerial propelling device comprising in combination, a driving shaft capable of axial movement, two propellers spaced apart on said shaft, one in operative, the

other in inoperative condition, means serving on said shaft being moved axially, to

cause one propeller to close up with the other one and means connected with said propellers for coupling them, after they.

have closed up.

2; Aerial propelling device comprising in combination, a driving shaft capable of ax- I in inoperative condition, means servingon' said shaft being moved axially, to cause one propeller to close up with the other one and means connected with said propellers for coupling them at an angle of-90, after they have closed up. a

3. Aerial propelling device comprising in combination, a driving shaft capable of axial movement, a propeller loose on said shaft at the end thereof another propeller on said shaft spaced apart from said loose propeller, a slot and key connection between said shaft and said other propeller, an abutment to the .rear of said-other propeller adapted to prevent it from following the axial motion of said shaft and coupling means on adjoining faces of said propellers.

In testimony whereof I afiix my signature.

CLAUDIUS DORNIER. 

